The present invention relates to machines for sewing buttons and specifically machines for the loading, advancing, aligning, sewing, and ejecting of buttons at a rapid pace. The prior art includes add-on units for use in combination with industrial sewing heads to accomplish these objects. These prior art devices have traditionally demanded multi-step, labor intensive installation including many adjustments to ensure proper placement of interrelated mechanical parts. Such prior art machines have used swing arms, rotary discs, or other elements to move buttons into position under a sewing needle and to subsequently displace the original button and advance a new button into position. U.S. Pat. Nos. 4,594,953, 4,884,517, and 5,062,373 all demonstrate prior art button loading or sewing devices.
The prior art also includes Mckee Button""s own xe2x80x9cButtonmatic 1097xe2x80x9d which employs a button feeding track to carry buttons from a vibrating dish type dispenser to a button chute located on a clamp assembly positioned generally below and behind the sewing needle. The clamp assembly of the 1097 receives buttons from the track into a button chute. A gear assembly with button hole pins aligns buttons within the chute to receive a needle and thread, and advances buttons to the sewing position. The 1097 also includes two side panel control plates mounted on the upper arm of the industrial sewing head. These side panel control plates use limit switches and precise adjustments to mechanically drive and control the various functions (rotate, advance, tilt, and return) that must be performed upon the button engaging portion of the 1097.
Air cylinders on the side panels drive extension rods that move hinged or sliding push rods to control the gear assembly that lies below on the clamp assembly. These air cylinders operate based upon the mechanical activation of limit switches that have been carefully arranged to contact moving parts, such as the push rods, in the desired sequence. This careful arrangement also determines the stroke length for the motion of parts and, as such, precise placement of limit switches is an important objective of set up and maintenance on the 1097.
The present invention is a simplified device for use with a sewing machine for the loading, aligning, and advancing of buttons. Control of a button orienting gear assembly is provided directly through a Programmable Logic Controller and electric air valves. The Controller coordinates the delivery of compressed air to various air cylinders. Each air cylinder, in turn, provides force to advance, tilt, or orient the gear assembly. A diagonal spring exerts a return force to bring the gear assembly back to a resting state after an advance and tilt step. By eliminating limit switch control as the primary means for gear assembly orientation, tilt, and advance, numerous parts are eliminated. The invention greatly reduces the time required to set-up an automatic button sewing attachment because it eliminates the need to carefully position a series of limit switches upon mounting plates with setting screws. In the prior art, these limit switches served to police the range of motion for mechanical push bars and to coordinate, in sequence, the steps to advance, tilt, and orient button engaging pins. Because the timed control of cylinder actuation through a Controller replaces the activation of air cylinders through mechanically activated limit switches, the precise adjustments of the prior art no longer need to be performed by the end user. In addition, the preferred embodiment of the present invention includes a compact arrangement of parts on a mounting surface, such as single clamp frame, rather than arrangement on a clamp frame and on separate side plates. This simplified design reduces installation steps, simplifies operation, and eliminates the movement of interrelated mechanical parts from the sides of the sewing heads (where they may more easily be damaged by contact from a user). The present invention may also be practiced with the use of motive means other than extension cylinders to drive the orient, advance and tilt steps.